In the field of electrophoresis, the sequencer device described in U.S. Pat. No. 4,828,669 represents a marked improvement in devices providing for such processing of proteins and nucleic acids. Such a device comprises at least one support for a gel plate assembly, and at least one buffer tank in liquid communication with the plate assembly. Most preferably, the support comprises a pair of fixed rails of fixed width, the buffer tank(s) being constructed to fit around the end(s) of the rails. As shown in the aforesaid patent, the rails are preferably inclined slightly from the vertical, to provide a resting surface for the plate assembly while it is being mounted on the support.
Although the above-mentioned device represents a marked improvement, it has one minor drawback--the width of the support as determined by the spacing of the fixed rails is fixed. This feature has in fact been standard on other electrophoresis devices as well. Gel plate assemblies come in a variety of widths, depending upon the number of sample lanes that are run within the gel. As a result, each electrophoresis device is usually dedicated to a fixed width, so that separate devices need to be constructed to accommodate differing widths of the gel plate assemblies.
More recently, an electrophoresis device has been described that allows for some width flexibility. The device, described on page 152 of the 1989 product catalog of BIORAD Laboratories as "Sequi-Gen Nucleic Acid Sequencing System", p. 152-154, allows a single base and lower buffer tank to be used with gel plate assemblies of two different widths, namely 21 cm and 38 cm. However, this device requires complete disassembly and reassembly to change the width size. That is, the entire gel plate support including the upper buffer tank is taken down and out of a "universal base" that provides the lower buffer tank, and a different gel plate support, gel plate assembly, and upper buffer tank is reassembled and inserted into that same base. Such variation in width is tedious and time-consuming, and requires different supports as well as a different upper buffer tank for each width, such tank being a fixed part of any given gel plate assembly.
Therefore, there has been a need prior to this invention to provide for a variable width electrophoresis device that accommodates variable widths of plates without requiring complete reassembly.